Federal agents were warned last year that a Minuteman group was planning to shut down a large section of freeway in central Arizona in an attempt to catch smugglers crossing through the desert, according to a secret law enforcement memo leaked last week.

The April 28, 2010 memo said the U.S. Border Patrol had received information that the group, which went by the name “A Concerned Citizen,” was recruiting people to help it shut down part or all of a 30-mile stretch of Interstate 8 between Casa Grande and Gila Bend.

The group reportedly wanted to carry out the operation to show support for Arizona’s strict new immigration law, known as SB1070, which had been signed by Gov. Jan Brewer five days prior.

The document didn’t say where the Border Patrol got its information, but it was clear the agency was worried about the development. It said the “tone of this information is quite unlike” that of better-publicized operations by Minuteman groups that had patrolled the borderlands.

“If this new operation happens,” the memo said, “there could be potential for human rights violations and a possibility of violence between armed civilians and smugglers or with law enforcement.”

The memo was among more than 700 files leaked Thursday by hacker group LulzSec, which said it obtained them by breaking into the email accounts of several Arizona Department of Public Safety officers. Many of the files, like this one, were bulletins from other agencies, marked as “law enforcement sensitive” and meant to be kept secret from the public.

Still, many of the files revealed incidents or plots that were never made public previously. Another memo leaked by the hacker group, for instance, revealed that Border Patrol agents found a roadside bomb along a smuggling route in 2009. The bomb exploded while it was being investigated, but it’s unclear whether anyone was injured.

In the memo about the freeway plot, a Border Patrol analyst said such activities had been stoked by recent events in Arizona. Specifically, the analyst mentioned the disbanding of the high-profile Minuteman Civil Defense Corps and the killing of rancher Robert Krentz, whose death, the analyst said, was “being touted as the work of a drug cartel.”

“It is not surprising that another contingent of Minutemen types has come to life,” the analyst said.

In addition to the freeway shutdown, which never was carried out, the memo also mentioned a phone call that a Border Patrol agent received March 27, 2010 from a man calling himself “Daniel Webster.” The man said the he and a group of “concerned citizens” had spotted several vehicles loaded with illegal immigrants on or near Interstate 8.

Agents searched the area but were unable to find the vehicles. The memo speculated that the phone call may have been somehow connected to the group planning to shut down the freeway.